The present invention relates to a cooking heater and, particularly, to a cooking heater capable of being used as either an electromagnetic induction heater or a high frequency induction heater.
An example of a conventional electromagnetic cooking heater is shown in FIG. 5, which employs a high frequency induction heater, or microwave oven. In FIG. 5, a housing 1 includes therein a heating room 2, a magnetron 3 for generating high frequency electromagnetic waves, a wave guide 4 for guiding the microwaves into the heating room 2 in which a material 5 to be cooked is disposed, a frying pan 6 which can be removed from the heating room and used for other cooking operations externally of the heater, a turntable 7 on which the frying pan can be mounted, and a motor 8 for driving the turntable 7.
For example, there may a case where the frying pan 6 is first heated by an external heat source such as a gas oven to sear the material 5 thereon and thereafter inserted into the heating room 2 to heat it uniformly with high frequency electromagnetic waves (typically, 2.45 GHz) generated by the magnetron 3, while rotating the turntable 7 by the motor 8.
In the so-called frying pan cooking system mentioned above, it is necessary to bring the frying pan from the external oven for searing to the electromagnetic heater which may be remote from the external oven.
Another conventional cooking heater comprises a high frequency heating device and an electromagnetic induction heating device provided integrally on the high frequency heating device. In this heater, material is induction-heated in the electromagnetic induction heater to sear it and then moved into the high frequency heating device for internal heating. This also requires the material to be moved from the upper electromagnetic device to the high frequency device, which is troublesome. Further, since the distance between an electromagnetic induction heating coil and a magnetic container is selected as large in view of thermal insulation, the coupling efficiency of magnetic flux is low and hence the heating efficency is relatively low compared with cooking with a gas range. Although there is another conventional device in which a shielded heater is provided within a heating room to implement searing, the heating efficiency thereof is also low.